An implantable sensor is useful for, in various diseases, e.g. a follow-up on the state of disease and monitoring therapeutic effects, and is one of the fields which have been actively studied in recent years. In particular in the treatment of diabetes, blood glucose control by continuous blood glucose measurements is said to contribute to the delayed progression of the state of disease and a decrease in development of complications.
Under the present circumstances, most of the diabetics collect a blood sample by puncturing a finger or the like, supply the sample to a blood glucose meter, and read a measured value to manage blood glucose by themselves. Such method, however, has problems in terms of distress of patients and simplicity, and the measurements are limited to a few times a day. Under the present circumstances, it is difficult to understand the trend and tendency of changes in blood glucose level by frequent measurements. For such reasons, it is believed that the usefulness of an implantable continuous blood glucose meter is high.
Meanwhile, technology for continuously measuring glucose concentrations in a living body has been developed for a long time. For example, there is technology in which glucose concentrations are measured by changes in the amount of fluorescence using a substance which emits fluorescence by a reversible reaction with glucose. As fluorescent substances of this type, Patent Literature 1 discloses a fluorescent compound having a fluorescent group of atoms, at least one phenylboronic acid region and at least one amine nitrogen, and a molecular structure in which the amine nitrogen is located near the phenylboronic acid region and intramolecularly binds to the phenylboronic acid. In addition, Patent Literature 2 discloses, as an indicator high molecule to detect the concentration of a sample in an aqueous environment, a copolymer of a hydrophilic monomer and an indicator monomer which has an excimer-forming polycyclic aromatic hydrocarbon such as an anthracene boronic acid ester derivative. Further, Patent Literature 3 discloses a method in which a fluorescent substance is directly immobilized on a solid phase such as a plastic film as a fluorescence sensor.
The sensor substances described in the above Patent Literatures 1 to 3 are, however, in the shape of films and the shape of sheets, and when the substances are implanted to use in a body, there is a problem of high invasiveness. For such problem, Patent Literature 4 suggests a sensor for measuring saccharides, in which a fluorescent sensor substance is immobilized on a base material such as a (meth)acrylamide film using a silane coupling agent and the like.